Class 10 Science Half-Yearly Model Paper 2026-27 (80 Marks) with Answer Key, English Medium | RBSE

Class 10 Science (Code 07) — Half-Yearly Model Paper 2026-27 (English Medium)

By NCERTClasses Team

Time: 3 hours 15 minutes  |  Maximum Marks: 80

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General Instructions

1. All questions are compulsory; marks are given in brackets against each question.
2. Syllabus: NCERT Science Class 10, Chapters 1–13 (Chapter 8: Heredity only).
3. Questions in Section D and Section E have internal choices.
4. In numerical problems, write the formula, substitution and unit.

Section A (Objective) — Questions 1–20, 1 mark each

MCQs, fill in the blanks, one-word answers, assertion-reason and case-based questions.

Section B — Questions 21–28, 2 marks each

Section C — Questions 29–34, 3 marks each

Section D — Questions 35–38, 4 marks each (with internal choice)

Section E — Questions 39–40, 5 marks each (with internal choice)

Unit-wise Marks Table

Answer Key and Marking Scheme

Marks are also to be awarded for any other correct method or answer.

1. (b) Displacement — Fe is more reactive, so it displaces Cu. [1]

2. Calcium carbonate (CaCO₃) [1]

3. (b) NaHCO₃ [1]

4. (a) — H⁺ ions are not formed in the absence of water. [1]

5. Mercury [1]

6. (c) Alkanes [1]

7. Alcohol (–OH) [1]

8. (b) Pepsin [1]

9. Alveolus (alveoli) [1]

10. (a) Auxin [1]

11. (b) Pollination [1]

12. (b) Y — the child always receives X from the mother. [1]

13. (b) virtual, erect and diminished [1]

14. (c) +5 D, because P = 100/20 = 5 D [1]

15. (b) concave [1]

16. (b) from the north pole to the south pole [1]

17. Electrical [1]

18. (c) 2 Ω, because 1/R = 1/3 + 1/6 = 1/2 [1]

19. (c) 3 A, because I = 6/2 = 3 A [1]

20. (b) 10% [1]

21. pH 2 is acidic (e.g. lemon juice) — 1; pH 10 is basic/alkaline (e.g. milk of magnesia) — 1. [2]

22. A sudden, rapid, involuntary response to a stimulus, controlled by the spinal cord without thinking by the brain — 1; example: withdrawing the hand on touching a hot object — 1. [2]

23. Sperm formation requires a temperature lower than normal body temperature — 1; the scrotum maintains a temperature 2–3 °C below body temperature — 1. [2]

24. Repeated division of regenerative cells forms an outgrowth (bud) on the body — 1; the bud develops into a small Hydra and, on maturing, detaches from the parent body — 1. [2]

25. Use of a condom — 1; diseases: gonorrhoea, syphilis, HIV-AIDS (any two) — 1. [2]

26. (i) The incident ray, the normal and the refracted ray all lie in the same plane — 1; (ii) Snell's law: sin i / sin r = constant (for a given colour of light and a given pair of media) — 1. [2]

27. The increase in the concentration of harmful chemicals (e.g. pesticides) at each successive trophic level of a food chain — 1; it is highest in the top consumer — 1. [2]

28. Ozone protects the Earth from the Sun's harmful ultraviolet (UV) radiation — 1; chlorofluorocarbons (CFCs) — 1. [2]

29. F₁: all Tt, all tall — 1; F₂ phenotypic ratio tall : dwarf = 3 : 1 — 1; genotypic ratio TT : Tt : tt = 1 : 2 : 1 — 1. [3]

30. Atmospheric particles scatter light of shorter wavelength (blue) more strongly, so the sky appears blue — 1; at sunrise/sunset the rays travel a longer path through the atmosphere — 1; most of the blue light is scattered away and the red light, of longer wavelength, reaches us — 1. [3]

31. CaSO₄.2H₂O → CaSO₄.½H₂O + 1½H₂O (373 K) — 1; it absorbs moisture and changes back to hard gypsum — 1; use: plaster for fractured bones / making toys / decoration (any one) — 1. [3]

32. HCl makes the medium acidic, activating pepsin, and kills bacteria — 1; trypsin digests proteins — 1; lipase (with bile-emulsified fats) digests fats — 1. [3]

33. Blood passes through the heart twice in one complete cycle: to the lungs (right → left side) and to the body (left → right side) — 1; oxygenated and deoxygenated blood do not mix — 1; this ensures an efficient supply of oxygen for high energy needs and for maintaining body temperature — 1. [3]

34. (i) Needed to make thyroxine; deficiency causes goitre — 1; (ii) pancreas; blood sugar rises, causing diabetes — 1; (iii) dwarfism — 1. [3]

35. 1 mark each (equation ½ + type ½): (a) Zn + H₂SO₄ → ZnSO₄ + H₂ — displacement; (b) BaCl₂ + Na₂SO₄ → BaSO₄↓ + 2NaCl — double displacement/precipitation; (c) 2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂ — decomposition; (d) 2H₂O → 2H₂ + O₂ — decomposition.
OR heat is released / absorbed — 1; temperature rises / falls (or energy difference) — 1; examples: CH₄ + 2O₂ → CO₂ + 2H₂O + heat; 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (sunlight) — 1 + 1. [4]

36. u = –25, f = –15; 1/v = 1/f – 1/u = –2/75 → v = –37.5 cm (in front of the mirror) — 1½; m = –v/u = –1.5 — ½; h′ = –7.5 cm — ½; real, inverted, magnified — 1.
OR u = –30, f = +20; 1/v = 1/20 – 1/30 = 1/60 → v = +60 cm — 1½; m = v/u = –2 — 1; real, inverted, magnified (2 times) — ½; P = 1/f = 5 D — 1. [4]

37. Stretch the thumb, forefinger and middle finger of the left hand mutually perpendicular: forefinger = magnetic field, middle finger = current, thumb = direction of force on the conductor — 2; the split ring reverses the direction of current in the coil after every half rotation, so the torque keeps acting in the same direction and the rotation is continuous — 2.
OR Earth wire: carries leakage current from the metallic body of an appliance to the ground, protecting from electric shock — 2; fuse: melts on overloading/short circuit and breaks the circuit, protecting the appliance — 2. [4]

38. Na (2,8,1) loses one electron to form Na⁺ (2,8) — 1; Cl (2,8,7) gains one electron to form Cl^– (2,8,8); the ionic bond forms by electrostatic attraction — 1; properties: high melting point / soluble in water / conduct electricity in molten state (any two) — 1 + 1.
OR Mineral: a naturally occurring metallic compound in the Earth's crust; ore: a mineral from which the metal can be extracted profitably — 1; roasting 2ZnS + 3O₂ → 2ZnO + 2SO₂ — 1½; reduction ZnO + C → Zn + CO — 1½. [4]

39. (a) R_s = 4 + 12 = 16 Ω — 1; I = 24/16 = 1.5 A — 1; (b) 1/R_p = 1/4 + 1/12 → R_p = 3 Ω — 1; I = 24/3 = 8 A — 1; P = VI = 24 × 8 = 192 W — 1.
OR R = V²/P = 220²/100 = 484 Ω — 1; I = P/V = 100/220 ≈ 0.45 A — 1; energy = 0.1 kW × 5 h × 30 = 15 kWh — 2; bill = 15 × 6 = ₹ 90 — 1. [5]

40. (a) Gaining or losing four electrons is energetically difficult; so carbon shares electrons and forms covalent bonds — 2; (b) same molecular formula, different structures — 1; CH₃CH₂CH₂CH₃ (butane) — ½; CH₃CH(CH₃)CH₃ (2-methylpropane) — 1½.
OR CH₃COOH + C₂H₅OH → CH₃COOC₂H₅ + H₂O (acid catalyst) — 1; ethyl ethanoate (an ester) — ½; fruity smell — ½; the hydrophilic end of the soap molecule stays in water and the hydrophobic end in oil/dirt, forming micelles, so the dirt is pulled into water — 3. [5]